Timer



M. FRIEDMAN Nov. 3, 19 70 TIMER 2 Sheets-Sheet 1 Filed NOV.- 25, 1968 INVENTQR.

MELVIN FRIEDMAN B 610mm and m /m X ATTORNEYS Nov. 3, 1970 M.- FRIEDMAN TIMER 2 Sheets-Sheet 2 Filed Nov. 25, 1968 FIG.2

lesm) F|G.3(b) FlG.3(c)- INVENTOR.

MELVIN FRIEDMAN 6mm and m nrrmnsm United States Patent Office 3,537,253 Patented Nov. 3, 1970 3,537,253 TIMER Melvin Friedman, Wakefield, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Delaware Filed Nov. 25, 1968, Ser. No. 778,661 Int. Cl. G04f 1/00 US. Cl. 58-223 6 Claims ABSTRACT on THE DISCLOSURE A timing mechanism operates to advance an element from a first movement limiting member to a second movement limiting member during a time interval proportional to the displacement between the two members. After each timing operation, the element is returned to the first member and a releasable brake means then automatically prevents further operation of the timer. The displacement between the movement limiting members is selectively variable in accordance with the duration of the interval to be timed.

SUMMARY OF THE INVENTION This invention involves a timing device and particularly a new and improved device for repeatedly timing an interval of selected duration.

The apparatus includes motor means for advancing an element, for example a pointer, at a constant velocity between a pair of members establishing limits beyond which the element cannot travel. A first limit is mounted on a movable member for reasons hereafter explained. The permissible movement of the movable member is sosmall, however, that insofar as the limit setting function is concerned, the limit setting member mounted thereon is considered stationary. A second limit setting member is carried by a knob which is movable to vary the displacement of the second limit from the first limit. The element is advanced from the first to the second limit setting member for timing an interval, the duration of which is proportional to the displacement beftweenthe limit setting members. The advanoeable element is reset to the first limit setting member after each timing operation for timing subsequent intervals. 'When' the advanceable element is reset to the first limit setting'member, the movable member is automatically moved the small amount permitted for bringing a brake means into operation to releasably prevent the motor means from advancing the element. The brake means is thereafter released to permit a further timing operation to occur. The apparatus is operated by simple steps consisting of releasing the brake and then resetting the pointer. I

"When the length of the interval being timed is to be changed, the knob is moved to change the displacement 1 between the limit setting members in accordance with a the desiredchange. A number of discrete stations for locking the knob against inadvertent movement may be associated with the knob. This enables the operator, during the interval setting operations, to set the knob 'at a particular station for timing a selected interval, to leave that station for timing another interval and then return it to precisely the same station for timing an interval of the exact same duration as the one first chosen. Without discrete interval setting stations the operator experiences difiiculty in reestablishing a previous setting. For example, if a continuously variable system is used, reliance must be placed in guesswork or very careful use of some type of calibration system.

The timer of this invention is particularly useful for timing the development of prints in photography according to the well-known diffusion transfer process. This process commonly includes the steps of exposing a photosensitive sheet to an imagewise distribution of light, superimposing the photosensitive sheet and a print receiving sheet, spreading a viscous fluid between the sheets and then, after a time interval, separating the sheets to reveal the developed print. In this operation, it is critical that the interval between spreading of the viscons fluid and the separation of the sheets be of a certain specified length. This length of time may vary in accordance with specific photographic materials being used and the conditions under which photography takes place.

Accordingly, the timer of this invention contains certain novel features which are particularly suited to the timing of print development. The ability of the timer to be set for timing a desired interval, reset and easily returned to the original setting, enables a photographer to quickly set the apparatus in accordance with the factors effecting development time. The brake means is operable to prevent operation of the motor only when the apparatus has been set to a fully wound condition wherein it is ready to begin a subsequent timing operation. It thereby prevents the operator from advancing the knob only part way from the second movement limiting member to the first. If partial resetting occurs, the timer immediately begins to run down, thus letting the operator know that it is not properly reset.

The system thus optimizes ease of timer operation, enables the timing interval to be accurately selected and insures that the apparatus is fully reset before timing operation begins.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a preferred embodiment of this invention;

FIG. 2 is a detailed view of a portion of the apparatus shown in FIG. 1; and

FIGS. 3a-3c show the apparatus in various of operation.

DETAILED DESCRIPTION OF THE DRAWINGS Reference is now made to FIG. 1 wherein a embodiment of this invention is illustrated.

Timer 10 includes a housing having front 12, back 14, motor 16 for rotating element 18 about axis 20, brake means 22 for inhibiting operation of motor 16 an knob 24. 1

Front portion 12 comprises opening 108,- det'ent and plate 112. Back 14 supports plate 26 and leaf springs 116, springs '106 being arranged peripherally of plate 26. Motor 16 may be of any desired construction. One example, illustrated in FIG. 2, comprises a spring drive, the operation of which is controlled by an escapement stages preferred mechanism mounted between plates 26 and 28, the plates being spaced apart'by posts 30. The spring drive comprises coil spring 32 wound around rotatable shaft 36 and having one end attached to the shaft and the other end anchored to a support 30. When the spring is tensioned, it is capable of rotating the shaft in a counterclockwise direction. The shaft extends through plate 28 and rotatably mounts rotatable element 18.

The angular velocity at which shaft 36 is rotatable is controlled by escapement mechanism 45 comprising gears 38 through 54 and a rocker arm 56 which serves as a balance member. Gears 40 and 42 are rotatably mounted on common axle 58; gears 44 and 46 are rotatably mounted on common axle 60; gears 48 and 50 on common axle 62 and gears 52 and 54 on common axle 64. Ends of axles 60, 62 and 64 are journaled in mounting plates 26 and 28 in any convenient manner, not shown. Plates 26 and 28 also form journals, not shown, for axle 58, at least one of which forms slot 65 to slidably mount one of the opposed ends of axle 58. This sliding movement permits gear 42 to be moved into and out of engagement with gear 44. Spring means 66 continuously bias axle 58 in the direction of arrow 68 to thereby continuously bias gear 42 into engagement with gear 44. Gear 42 is movable out of engagement with gear 44, against the bias of spring means 66, during the cocking of spring 32, as will hereafter be described.

Rotatable element 18 takes the form of a generally circular disc 70 having finger 72 projecting therefrom. The element defines a pair of inclined surfaces 73 terminating in manually engageable vertical surfaces 74 facing in opposite directions. Surfaces 73 and 74 enable an operator to engage element 18 and rewind the timer subsequent to each timing operation.

Brake means 22 is releasably engageable with escapement mechanism 45 for preventing operation of motor 16. Brake means 22 includes member 76 pivotally mounted upon plate 26 by pin 78. Member 76 supports bent up the clockwise direction being controlled by stop 88 and movement in the counterclockwise direction by a limited stop 90. counterclockwise rotation of plate 28 disengages bent up portion 80 from gear 54 to permit operation of motor 16; clockwise rotation of the plate brings portion 80 into engagement with gear 54 to prevent operation of the motor.

Knob 24 is configured as a ring circumscribing axis 20 and is manually rotatable thereabout. It comprises a forwardly directed face 92 bearing time related indicia 93, depending sides 94 and 96 forming concentric cylinders, projection 102, flange 98 and manually engageable serrations 116.

- Flange 98 extends peripherally outward from side 94 and defines a flat bearing surface 104 on one side and engageable surface 100 on the opposite side. Engageable surface 100 comprises a number of flat surfaces 101 interposed between a number of elongated, radially extending ridges 103 having curved upper surfaces 105. Side 96 en- "circles motor 16 and surface 104 rests upon leaf springs 106. Springs 106 serve as a bearing support for knob 24 and provide a bias for urging it toward front 12, along axis 20. Side 94 depends toward plate 28 to form projection 102 which extends radially inward toward axis 20.

Projection 102 and post 84 each extend into the arcuate path of finger 72 on opposite sides thereof, so that post 84 limits clockwise rotary movement of finger 72 and projection102 limits counterclockwise movement of the finger. The angular displacement between projection 102 and post 84 is variable by rotating the projection about axis 20 in a manner hereafter described while the position of post 84 remains fixed thereby to select the duration of an interval to be timed. (For purpose of interval selection, the position of post 84 is considered fixed since the very small angular rotation thereof which occurs as a consequence of plate 28 being pivotable between narrow limits is inconsequential.)

Front 12 of the housing defines opening 108 of generally circular configuration and having a diameter slightly in excess of the overall diameter flange 98. Engaging means comprising detent 110 extends radially inward from the circumference of opening 108 for interception with engageable surface on flange .98. Front 12 includes plate 112 afiixed thereto on the side opposite the side facing back 14. Plate 112 includes substantially circularly configured opening 114 superimposed with opening 108. The diameter of opening 114 slightly exceeds the diameter of the cylinder defined by side 94. Opening 114 permits face 92 but not flange 98 to protrude therethrough.

When the apparatus is assembled, curved surfaces of ridges 103 bear against the under surface of plate 112 adjacent the periphery of opening 114. In this condition detent extends between a pair of ridges 103 in overlapping relationship with a flat surface 101 to prevent roation of knob 24. The ridges 103 are continuously biased toward engagement with the under surface of plate 112 by springs 106. In this manner each surface 101 and the two ridges 103 flanking it establish a discrete engageable station.

Operation of the apparatus will now be described. Reference is made to FIGS. 1 and 3(a) wherein the apparatus is shown in the fully wound, braked position with knob 24 at its zero time setting. To time an interval, for example one of fifteen seconds, the knob is manually grasped at serrations 116 and pressed inwardly along axis 20 against the bias of springs 106. Inward movement removes ridges 103 from a position wherein they are engageable by detent 110, thereby removing all engageable stations from the detent. The knob is then rotated counterclockwise until indicia 93 designating fifteen seconds appears exactly beneath indicator 83 on lever 82. Release of the knob permits springs 106 to move the knob to a position wherein detent 110 engages one of the engageable stations. Projection 102 is thereby rotated clockwise through a particular angular displacement corresponding to location of the fifteen second indicia beneath arrow 68 and releasably retained in that angularly displace position. This condition is illustrated by FIG. 3(b).

Lever 82 is then rotated counterclockwise until it abuts stop 90 to move ben up portion 80 of member 76 from engagement with the teeth of gear 54. This releases the escapement mechanism so that motor means 16 may advance finger 72 from post 84 toward and to projection 102. See FIG. 3c. Operation of the motor means is as follows: Spring 32 rotates shaft 36, and thus element 18, and drives gear 38 counterclockwise. As gear 38 rotates, it assists spring 66 in establishing firm engagement between gear 38 and gear 40 and causes gear 40 to rotate clockwise. Accordingly, as is well known in the art, all the gears of gear train 45 rotate under the driving influence of spring 32. Rocker arm 56 engages teeth of gear,54 to control the speed at which the gears of the escapment mechanism are permitted to rotate and establish a constant angular velocity at which spring 32 drives shaft 36. The apparatus continues to operate until finger 72 moves into abutment with projection 102. The escapement mechanism is so calibrated that the time required for finger 72 to move from post 84 to projection 102 corresponds to the time indicia located directly beneath arrow 68 on lever 82. The vibration of rocker arm 56 produces audible sound, the cessation of which may serve to indicate to the user that the timing operation is complete. a

After each use, the apparatus is rewound and motor means 16 is automatically braked. Element 18 is advanced clockwise until finger 72 contacts post 84 and shifts member 76 from its position adjacent stop 90 to a position adjacent stop 88. Movement of member 76 brings portion 80 thereof back into engagement with the teeth of gear 54 to prohibit rotation of this gear and thereby act as a brake on the escapement mechanism which, in turn, prohibits the unwinding of drive spring 32.

During rewinding, the action of gear 38 on gear 40 urges axle 58 in a direction opposite that indicated by arrow 68, against the bias of spring 66 and thereby removes gear 42 from gear 44. In this manner, the gear train is disengaged during rewinding so there is no tendency to force the escapement mechanism to operate in the reverse direction. When element 18 is released after rewinding, a small increment of counterclockwise movement occurs to take up the slack in the system and permit spring 68 to advance shaft 58 in the direction of arrow 60 to thereby bring gear 42 into engagement with gear 44. The system is now reset to time another fifteen second interval. It should be observed that the members rotating the movement of finger 72 require no adjustment for successive timing operations. The operation takes place merely by the performance of this simple step or releasing the brake by means of lever 84 to initiate operation and subsequently rewinding the apparatus by advancing member 18 clockwise to a position firmly against post 84. The system always begins to operate from a fully wound condition to take advantage of the more predictable action of a tightly coiled spring, thereby to increase accuracy of operation.

When the timing interval is to be changed, projection 102 is repositioned by the manipulation and rotation of knob 24 in the manner described above. The knob is simply rotated until the indicia designating the desired time interval appears adjacent indicator 83. The apparatus may now be operated to repeatedly time intervals .of the newly selected length.

. The exposure stations formed by flat surfaces 101 and ridges 103 enable the operator to select a setting for any desired time interval which is exactly the same as a setting previously chosen for that time interval. There is only one engageable station corresponding to the location of indicia pertaining to a particular time interval beneath indicator 83. For example, if the apparatus is set for timing intervals of fifteen seconds and then reset to time intervals of sixty seconds, it may be returned to a position for timing intervals of fifteen seconds and, due to the discrete exposure stations, the setting will be exactly the same as the setting for the previous timing of fifteen second intervals.

It may now be appreciated that this invention provides an easily operated resettable timer facilitating accurate selection of an interval to be timed wherein the apparatus must be fully reset after each timing operation for enabling it to perform a subsequent timing operation.

It should be understood that the terms inward, outward, clockwise, counterclockwise and the like are used in the foregoing disclosure to describe movement of various elements as seen in the figures and are not intended to be used in a limiting sense.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A timer comprising:

(a) means defining a first movement limiting member;

(b) a knob defining a second movement limiting member, said knob being rotatable about an axis to position said second movement limiting member at a selected angular displacement from said first movement limiting member;

() an element rotatable about said axis between limits set by said first and second movement limiting members, rotation of said element in one direction being limited by said first member and rotation of said element in the other direction being limited by said second member;

(d) motor means for rotating said element from said first movement limiting member toward and to said second movement limiting member during a time interval dependent upon the selected angular displacement; and

(e) releasable brake means for preventing operation of said motor in response to return of said element to said first movement limiting member.

2. A timer according to claim 1 further comprising:

(a) engaging means;

(b) means on said knob engageable by said engaging means;

(0) means biasing said knob in one direction along said axis to a position wherein said engageable means is engaged by said engaging means for preventing rotation of said knob, said knob being movable in the opposite direction along said axis against the action of said biasing means for disengaging said engageable means from said engaging means to permit rotation of said knob, thereby to permit variation in the angular displacement of said second movemen limiting member from said first movement limiting member.

3. A timer according to claim 2 wherein said engageable means defines a number of discrete engageable stations arranged circularly of said axis, and said engaging means is engageable with any selected one of said stations, thereby to enable said second movement limiting member to be displaced from said first movement limiting member by discrete angular increments.

4. A timer comprising:

(a) rotatable element defining an ofiset which travels in an arcuate path when said element is rotated;

(b) a spring driven motor for rotating said element in one direction about an axis, said element being rotatable in the opposite direction about said axis for winding the motor spring;

(0) a knob rotatable about said axis, said knob defining a projection extending into the path of movement of said offset and a peripheral flange comprising an engageable surface substantially normal to said axis;

((1) engaging means located adjacent said peripheral flange for cooperation with said engageable surface;

(e) means resiliently biasing said knob for movement along said axis for moving said engageable surface toward engagement with said engaging means, said knob being restrained against rotation when said engageable surface is engaged by said engageable means and released for rotation about said axis when said knob is advanced along said axis against the resilient bias of said biasing means; and

(f) a pivotally mounted member defining:

(1) a post extending into the said arcuate path of said offset on a side thereof opposite the projection for limiting rotation of said element in said opposite direction, said post being shiftable in response to firm movement of said offset against said post; and

(2) means movable into braking engagement with said motor means in response to shifting of said post by said offset;

said motor being effective to drive said offset from said post to said projection during a time interval dependent upon the angular displacement of said projection from said post, said projection being selectively movable to a number of angular displaced positions from said post for selecting an interval for timing. 5. A timer comprising: (a) a limit setting member;

(b) a travelling element movable to and .fromsaid limit setting member; 1 ,o

, (c) motor means for moving said travelling element away from said limit setting member for designating the passage of an amount of time;

(d) means for permitting return of said travelling element to said limit setting member; and

(e) brake means responsive to said return for prov'iding a releasable braking action to prevent further I operation of said motor means.

6. A timer. accordingv to claim 5 further comprising manually actuated means for'releasing said brake'means to permit operation of said motor means.

J i o References Cited I I ,UNITED STATES PATENTS 9/ 1967 "Felsenfe'ld '58;""2 1'.1i3 RICHARD B. WILKINSON, Primary Examiner Y L. R; FRANKLIN, Assistant Examiner 'U.S. cl; X.R."

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